Osiris had a brother. His name was Set. Set was jealous that Osiris was pharaoh. Set tried to kill Osiris.
First, he tried by putting Osiris in a coffin, then cutting Osiris into pieces. The coffin idea didn't work.
Cutting Osiris into peices worked though. Isis (Osiris's wife) Collected all of Osiris's pieces and
brought them to Anubis. Anubis couldn't bring Osiris back to life. When Horus (Osiris's son) found out, he killed Set.

This is why the Egyptians made the Crook and Flail.